Layers of the Skin

Epidermis(location)

stratified squamous epithelium

Epidermis(parts)

dead cells packed with keratin, avascular, contains nerve endings for pressure/pain

Stem Cells

in the stratum basale, give rise to keratinocytes

Keratinocytes

in most epidermal cells, produce keratin

Melanocytes

in the tratum basale, branched processes spread to keratinocytes, produce melanin

Tactile Cells

in the stratum basale, touch receptors associated with dermal n. fibers

Dendritic Cells

in the stratum spinosum & stratum
granulosum, Macrophages originating in bone marrow

Stratum basale

Stem cells divide, Keratinocytes migrate to surface, also some melanocytes & tactile cells

Stratum spinosum

Layers of keratinocytes w/ desmosomes, contains some dendritic cells

Stratum granulosum

help create a waterproof barrier to prevent water loss from the body. (3-5 layers of flattened keratinocytes)

Stratum lucidum

Keratinocytes in this layer are now dead, protects the body from damage in areas that are most likely to be damaged

Stratum corneum

Many layers (up to 30) of dead cells, keratinocytes dead in this layer, Resists abrasion, penetration, & water loss

Journey of Keratinocytes

produced from mitosis, Migrate apically, Flatten & make more products, Reach surface in 30-40 days, flake off.(faster in response to injuries)(slows with age)

Dermis(parts)

made of connective tissues, mostly collagen, vascularized, houses hair follicles and nail roots, area attachment for facial muscles

Papillary Layer(in dermis)

Superficial, Areolar tissue, Allows for WBC mobility, Highly vascularized

Reticular Layer(in dermis)

Deep, Dense irregular
connective tissue, Tears in collagen fibers caused by rapid stretching produces
striae (stretch marks)

Hypodermis(parts)

Subcutaneous tissue, Areolar & adipose connective tissues, Binds skin to underlying tissues

Hypodermis(function)

protection, insulation, storing energy, connecting skins to muscles and bones

Dermis(function)

protection, sensation, thermoregulation, support

Subcutaneous fat

Energy reserves, insulation, & cushioning, Thicker in women, Thinner in infants & elderly

Constitutive skin color

genetically determined skin color

Facultative skin color

temporary change in skin color that occurs when the skin produces more melanin in response to exposure to UV

Melanin

biomolecules that give skin color

Eumelanin(color)

brownish-black

Pheomelanin(color)

reddish-yellow

Flexion creases

Skin bound to deep tissues along these lines

Freckles/Moles

Aggregations of melanocytes

Hemangiomas

Patches of discoloration caused by benign tumors of dermal capillaries